Pulse or digital communications – Transmitters – Antinoise or distortion
Reexamination Certificate
2005-09-06
2005-09-06
Patel, Jay K. (Department: 2637)
Pulse or digital communications
Transmitters
Antinoise or distortion
C455S114300
Reexamination Certificate
active
06940919
ABSTRACT:
An apparatus and method for generating an envelope predistorted radio frequency signal which avoids undesirable spurious emissions. A complex baseband signal, having an in-phase component I and a quadrature component Q, is sampled and filtered in a sampling circuit and filter circuit to obtain samples Ikof the in-phase component and samples Qk, the quadrature component. The magnitude xkof each sample pair is determined in a first calculation circuit. An amplitude and phase distortion factor Dk, based on scaled values of the archyperbolic tangent and the hyperbolic tangent of the baseband sample magnitude is determined in further calculation circuit and a multiplier. Each sample Ikof the in-phase component and Qkof the quadrature component is multiplied by the corresponding distortion factor Dk, and the resulting predistorted components combined and upconverted to provide a predistorted baseband signal which is amplified in a power amplifier having hyperbolic tangent distortion.
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Meek Jacob
Miller John A.
Northrop Grumman Corporation
Patel Jay K.
Warn, Hoffmann, Miller & LaLone, P.C.
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